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The length of the tarsus and wing, and the weight of the Dipper were measured in four mountain ranges in Spain (Cantabrian Mountains, western Pyrenees, the Central Mountains and Sierra Nevada). Birds from the Sierra Nevada were the largest but there were no significant differences among the other three areas. In the north, the range of the C. c. cinclus and C. c. aquaticus subspecies overlapped. In the south only aquaticus was present and in the central mountains only cinclus. The biometrics of cinclus in the north and centre were similar but aquaticus was larger in the south than the north. Spanish populations of C. cinclus thus appear to go against the predictions of Bergmann's rule. The residual index (RI) was calculated for individual birds from the regression of mass/tarsus length. RI was higher in males than females in the northern populations, but the same in the centre and south. According to this index, males (but not females) were heavier than the theoretical weight in the north and lighter in the centre and southern ranges. Some other variations in the Spanish populations are also discussed.

The first stage of the Siberian Knot's autumn migration between its breeding grounds in Taimyr, Siberia and the W European tidal flats is still poorly understood, despite our expanding knowledge of this species. This paper analyses data (1988–1995) on the numbers of Knots and the timing of their migration in the Puck Bay region of the Baltic Sea (N Poland). The timing varied greatly between seasons. The timing of adult migration is linked to breeding success. In seasons with low breeding success both males and females leave the breeding grounds earlier, and the correlation between the mean date of adult migration and the number of juveniles is consistent with this phenology. The differences between the departure dates from the Taimyr breeding grounds provided by published sources and the dates of arrival at Puck Bay suggest that Knots cross the northern tundra regions very quickly (at least, the earliest birds to arrive do so). The numbers of juvenile Knots turning up on the Polish coast appear to depend not only on the lemming cycle in the breeding grounds, but also on other factors, like local weather conditions, which could influence the number of juveniles observed.

The pattern of autumn migration of the Robin was studied through an analysis of daily dynamics for the birds caught in the years 1984–1997 at four ringing stations (two on the Baltic coast and two in inland Poland). In a given year, migration dynamics was found to be distinctly similar at all stations. It showed conspicuous consistence (± 2 days) in the dates with peak numbers. This could be explained by assuming that Robins take off at the same time across a large breeding ground, and arrive almost simultaneously at stopover sites located over extensive areas. Moreover, migration dynamics from year to year at a given station was also remarkably similar, though this phenomenon was more distinct at the inland stations than at the coastal ones. Day-to-day fluctuations in numbers were on an average the highest at the coastal station most exposed to variable weather, the lowest at the inland stations, and intermediate at the more “sheltered” of the coastal station. The paper discusses the extent to which such results can reflect the influence of weather conditions on passage, or else a precise internal (physiological and genetic) mechanism responsible for the timing of migration.

Ninety-nine road-killed Barn Swallows were found during three years of studies on a 48.8 km road network in an intensively farmed landscape in SW Poland. Nearly 88% of all road-kills were recorded in built-up areas and on road sections in their vicinity. The average number of road-kills per 1 km of roads was over twenty times higher in built-up areas than in open agricultural landscape (6.74 vs 0.33 road-kills/1 km). This paper investigates the influence of environmental factors (lines of trees along roads, number of livestock, volume of traffic, number of inhabitants) on the level of Barn Swallow mortality on the roads in question. During the breeding season the number of birds killed in built-up areas was related positively to the number of cattle reared, the overall number of livestock (including pigs) and the number of inhabitants. In the multiple regression model following stepwise forward selection, the number of cattle explained 41 % of the variance in the size of the whole-year road mortality of swallows in the built-up area. During the autumn migration period the length of tree-lined road sections in the built-up area had an significant influence on road-kill frequency, explaining 36% of the variance in mortality. Mortality was high on tree-lined sections of road in adverse weather conditions.

Long-term observations (1991–2002) have shown that Hawfinches breed throughout the extensive Białowieża Forest; they are only slightly less numerous in the forest interior than at its edge. Population size, habitat and nest sites were studied in two plots in the species-optimal habitat (continuous oak-lime-hornbeam old-growth). The true breeding density there was 4.0–8.4, reaching as much as 15.2 p/10 ha in some years, while, according to the combined territory-mapping method for the same period, it was, on average, 5.8 pairs/10 ha in oak-lime-hornbeam, 3.3 pairs/10 ha in riparian ash-alder, but less than 0.5 pairs/10 ha in mixed coniferous-deciduous or young deciduous stands (marginal habitats for this species). Being among the most numerous species in the Białowieża Forest bird community, Hawfinches hold small nesting territories that are sometimes loosely grouped. Nests are built at an average height of 18.1 (7–34) m in the tree canopy. Hornbeams are the preferred tree species for nesting in the oak-lime-hornbeam stands (also clumps of mistletoe in the continental maple), while black alders in the riparian woodland. Originally, the Hawfinch must have been a species of old, high forests. Its recent nesting elsewhere — low in bushes or, preferably, along woodland edges — is likely to be a secondarily acquired trait; it could also be due to a bias — Hawfinch nests are more easily discovered in such localities.

Avifaunas of three large cities (Hamburg, Berlin and Warsaw) situated in the northern lowlands of Central Europe along an 850-km-long west-east line were compared. Estimates of several species' breeding populations in these cities were used to calculate their densities in the total area of breeding habitat in each city used by the species in question. The relationship of the densities of several common species was compared. Of 39 species analysed, 18 showed higher densities in Hamburg, 4 in Warsaw and 2 in Berlin. A gradient of increasing density from Warsaw to Berlin and Hamburg (Western gradient) was found for 16 species: Columba palumbus, Troglodytes troglodytes, Prunella modularis, Turdus merula, T. philomelos, T. viscivorus, Sylvia atricapilla, Phylloscopus collybita, Ph. trochilus, Regulus regulus, R. ignicapillus, Garrulus glandarius, Parus cristatus, Certhia brachydactyla, Fringilla coelebs, Pyrrhula pyrrhula. An opposite (Eastern) gradient was found for only 3 species: Columba livia f. domestica, Oriolus oriolus and Passer domesticus. Suggested causes for most of the larger differences among the three cities in the densities of particular species are the variation in the richness of vegetation (higher in both German cities) and differences in the stage of synurbization (i.e. adaptation to the urban environment) of specific avian species. In a few cases, factors such as the geographic range of a species, the attitude of humans (in the case of the Feral Pigeon), and specific, slight variations in habitat are put forward to explain the differences found.

During seven winter seasons (1993/1994–1999/2000) 107 roadside counts (28 km each) in agricultural area of south-western Poland were conducted. From among 1526 Buzzards, 1293 were recorded in winter months (November—February) and 233 in March. Birds were non-randomly distributed on nine vegetation types met along the transect route. Permanent papilionaceous crops, along with cereal stubbles, margin habitats, meadows and maize stubbles were preferentially used, whereas bare tillage and winter cereals were avoided. In general, Buzzards preferred habitats of the least amount in the studied area and avoided those which dominated. These data support the idea of high importance of small landscape structures for the biodiversity protection in intensively used farmland. During winter months, most Buzzards (59.5%) were perched when first sighted, most often on trees and in the middle part of their height. The percent of birds sitting on the ground amounted to 34.7%. The smallest amount of individuals (5.8% ) was observed flying (flap-sailing, hovering and soaring), however this activity significantly increased in March (up to 17.1%). The significance of various hunting methods for wintering Buzzards is discussed. Even though it is a typical perch hunting raptor, the method of hunting from the ground seems to be particularly suitable for the conditions of winter farmland: common scarcity of perches, poor and low vegetation, local and temporary prey concentrations.

A multivariate analysis was carried out in order to investigate the most influential habitat variables and related features in the selection of breeding cliffs by the Griffon Vulture in Crete. The species was found nesting in mid-altitude areas, close to stock-raising units, on high limestone cliffs, which were also well protected against the prevailing winds of the island. A principal components analysis, which explained 53% of the total variance of the variables examined, differentiated Griffon Vulture colonies in relation to their isolation from other colonies, accessibility to humans and proximity to food resources. In addition, a stepwise discriminant function analysis between breeding and random cliffs included the height of the cliff, its substratum, the altitude, and the distance to the stock breeding unit in a model that successfully classified 97.1% of the nesting and 88.2% of the random cliffs. In comparison to continental regions the Griffon Vulture colonies in Crete were located on higher cliffs but at a lower altitude. This fact should be attributed to the species nesting on steep coastal cliffs close to the livestock's wintering areas.

During a four-year study of the breeding biology and ecology of an atypical population of Barn Swallows nesting in 13 abandoned post-war bomb shelters, the unexpected presence of foreign juveniles in active nests with nestlings was recorded on eight occasions. In five cases, single birds were noted, and in the other three, two foreign individuals were observed. The average age of the nestlings joined by foreign juveniles was 11.6 days (SE = 1.08, range 8–16), while the average age of the latter birds recorded with the nestlings was 23.2 ± 1.02 days (range 20–25). The mean distance between the hatching and parasitised nests was 0.9 ± 0.11 m (range 0.5–1.2). This unusual behaviour in swallows seems to be deliberate and is aimed at choosing a nest with nestlings in order to obtain extra food from experienced adult birds rather than an error caused by the darkness in the shelter.

The habitat and nest sites of an island-endemic, the Másafuera Grey-flanked Cinclodes, are described for the first time. The species breeds only in natural cavities in steep rock-walls and rocky slopes or ridges. The nest entrance diameter ranges from 5.5 to 20 cm, the nest chamber being placed within the rock so as to be invisible from the outside. The nest sites found — solely on Alejandro Selkirk Island — were located from a little above the sea-level to the summit region, the preferred habitats being barren canyon bottoms with small streams, and humid alpine plateaus. Nesting extends from early December to late January, indicating a core breeding season from November to January. Fledgling numbers per clutch average about two.

Territoriality in Red-breasted Flycatchers was studied in the Białowieża Forest of Eastern Poland during five consecutive breeding seasons (2000–2004). In total 99 males were individually marked, and evidence of polyterritoriality was found in 10% of them. The proportion of polyterritorial males varied from 0% (in 2003) to 13.6% (in 2001). The mean distance between the first and second territories was 278 m (± 179.37, n = 10). The rate of polyterritoriality was not related to age class, as older males defended dual territories that were, on average, not more distantly separated than those of younger males. One case of polygyny was recorded. To our knowledge, this is the first evidence for polyteritoriality and polygyny in male Red-breasted Flycatchers.